Extruding surface while keeping the shape
Inset the face

Go into edit mode. Select the face. right-click
Press I to inset the face.

OR

Press W to open the Specials menu.
From the Specials menu, choose Inset Faces. I

OR

PressCtrl+F to open the Faces menu.
From the Faces menu, choose Inset Faces. I

OR

Choose Mesh &gt; Faces &gt; Inset Faces from the edit mode menu.